Relatively recently there have been developed various proposals for ignition systems for internal combustion engines (ICE) wherein a quantity of fuel/air mixture disposed within a combustion chamber of the engine is ignited by means of one or more flame fronts. Such flame fronts are derived from a single flame front which is initiated within an auxiliary pre-combustion chamber which, in turn, is physically separated from the main combustion chamber of the ICE. From this initial ignition point, the flame propagates along a channel leading from the initial ignition point to the combustion chamber. Herein at times, this channel is referred to synonymously as the “first channel” or as the “first central channel”. The flame front moving through the first channel is divided into one or more flame fronts, each of which exits separately, from the channel and into the combustion chamber via respective lateral channels. Commonly, a flame front exits into the combustion chamber via the first channel and separate flame fronts exits into the combustion chamber via the one or more lateral channels. Much attention has been paid to the respective directional orientation of the first channel and the lateral channels (and their associated flame fronts) into the combustion chamber, with the desire to maximize the simultaneity and completeness of ignition of the fuel/air mixture disposed within the combustion chamber.
Of major concern in certain flame front-type ignition systems is how one goes about installation of a flame front ignition system in operative relationship to an existing internal ICE so that the orientation of the flame fronts from the flame cone are directed toward specific locations within the combustion chamber which have been determined to produce maximized simultaneity of ignition and completeness of combustion of the fuel/air mixture disposed within the combustion chamber. This problem is of particular significance when seeking to convert an ICE from a non-flame front ignition system to a flame front ignition system.
It is to be noted that in all known four-stroke ICEs, there is an internal combustion chamber which is fitted with at least one intake valve, at least one exhaust valve and some means, most commonly at least one spark plug, which serves to ignite a fuel/air mixture drawn into the combustion chamber via the intake valve. In certain of the prior art non-flame front ignition systems the spark plug is threaded into a throughbore provided through the wall thickness of the head of the ICE to the extent that the electrodes of the spark plug are exposed directly within the combustion chamber. Herein, this non-flame cone embodiment is at times referred to as the “standard” system.
On the other hand, in flame front ignition systems, most commonly, the electrodes of the spark plug are disposed within an auxiliary pre-combustion chamber which is at least semi-isolated from the interior of the combustion chamber. In the compression stroke of the ICE, fuel/air mixture from the combustion chamber is fed into the auxiliary pre-combustion chamber. Thereafter, the firing of the spark plug ignites the fuel/air mixture within the auxiliary pre-combustion chamber and the flame front which is developed propagates along the first channel toward the combustion chamber. In this system, before this flame front exits the first channel, the initial flame front is divided in multiple separate flame fronts as by means of a flame cone. These multiple flame fronts exit the flame cone into the combustion chamber where they ignite the fuel/air mixture disposed with the combustion chamber.
In one embodiment of a flame front pre-ignition system as described in Applicant's copending application Ser. No. 11/622,801, filed Jan. 12, 2007, entitled SPARK IGNITION MODIFIER MODULE AND METHOD, once the desired orientation of flame fronts exiting a flame cone are determined, a flame cone having such oriented exit channels may be manufactured. One prior art technique for aligning such flame cone within the throughbore, hence the directionality of its exiting flame fronts, includes the use of a flame cone which is insertable into the throughbore from a location internally of the combustion chamber. In this latter technique, the flame cone is threaded into the inboard end of the throughbore until the flame cone is securely, but not necessarily fully, threaded into the throughbore. At this point, the rotation of the flame cone within the throughbore is adjusted such that the directionality of the flame exit ports are in their desired orientation with respect to pertinent ones of the elements disposed within the combustion chamber of the ICE. Thereupon means is required to lock the flame cone in its selected rotational position within the throughbore. Thereafter the spark plug is inserted into the opposite external end of the throughbore and/or the outboard end of the flame cone. This technique requires access to the combustion chamber of the ICE, e.g., removal of the cover of the head of the engine.
In another technique, described in Applicant's U.S. Pat. No. 7,104,246, entitled SPARK AMPLIFIER, the rotational position of the exit channels of the flame cone are established in the course of manufacturing the flame cone and the flame cone is thereafter inserted into the throughbore starting at the outboard open end of the throughbore (i.e. starting externally of the head). This technique addresses the problem of bottoming out the threading of the flame cone into the throughbore at a location which is inconsistent with the desired rotational orientation of the flame cone, hence the rotational orientation of its exit flame front channels.
It is recognized that two stroke engines, like in engines for chain saws, etc., do not have valves. Moreover some engines have more than one spark plug per cylinder. One skilled in the art will further recognize the applicability of the present invention to these and/or other internal combustion engines.